Inspection Procedure 2: M.U.T.-III cannot communicate with EPS system. ECU power supply circuit system check










COMMENTS ON TROUBLE SYMPTOM


If the M.U.T.-III cannot communicate with the EPS system, the CAN bus lines may be defective. If the EPS system does not operate (power assist is not available), the EPS-ECU or its power supply circuit may be defective.

PROBABLE CAUSES



DIAGNOSIS PROCEDURE

STEP 1. Connector and terminal check

  • Check the B-114 EPS-ECU connector and junction block connector for improper engagement, terminal damage, or drawn-in terminal to the connector case.

Q. Are the connector and terminal normal?
Go to Step 2.
Repair the connector(s) or terminal(s).

STEP 2. Voltage measurement at B-114 EPS-ECU connector

  • Disconnect the connector and measure at the wiring harness side.
  • Turn the electric motor switch to the "ON" position.
  • Measure the voltage between B-114 EPS-ECU connector terminal No. 3 and the body earth.
OK: Battery voltage

Q. Is the check result normal?
Go to Step 3.
Go to Step 5.

STEP 3. Voltage measurement at B-114 EPS-ECU connector

  • Disconnect the connector and measure at the wiring harness side.
  • Measure the voltage between B-114 EPS-ECU connector terminal No. 2 and the body earth.
OK: Battery voltage

Q. Is the check result normal?
Go to Step 4.
Go to Step 6.

STEP 4. Measure the resistance at B-114 EPS-ECU connector.

  • Disconnect the connector and measure at the wiring harness side.
  • Measure the resistance between B-114 EPS-ECU connector terminal No. 1 and the body earth.
OK: Continuity exists (2 Ω or less).

Q. Is the check result normal?
Go to Step 8.
Go to Step 7.

STEP 5. Wiring harness check
note Before the wiring harness inspection, check the junction block connectors B-302 and B-306, and repair if necessary.

  • Check the wiring harness between B-114 EPS-ECU connector terminal No. 3 and junction block connector for any abnormality.

Q. Is the wiring harness normal?
Go to Step 8.
Repair the wiring harness.

STEP 6. Wiring harness check

  • Check the wiring harness between B-114 EPS-ECU connector terminal No. 2 and the fusible link No. 23 for any abnormality.

Q. Is the wiring harness normal?
Go to Step 8.
Repair the wiring harness.

STEP 7. Wiring harness check

  • Check the wiring harness between B-114 EPS-ECU connector and the body earth for any abnormality.

Q. Is the wiring harness normal?
Go to Step 8.
Repair the wiring harness.

STEP 8. Check the trouble symptom.

Q. Is the check result normal?
An intermittent malfunction may be present. (Refer to GROUP 00 - How to Cope with Intermittent Malfunction .)
Replace EPS-ECU.(Refer to .)




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